Motor with heat dissipation structure

ABSTRACT

A motor includes a cylindrical housing, a cooling fan, and a rotating shaft. The cylindrical housing defines at least one upstream through hole at its circumferential wall. The cooling fan is mounted at the rotating shaft for generating airflow towards the cylindrical housing for dissipating the heat generated in the motor. The hollow hood is mounted to the cylindrical housing such that a head portion is located above the upstream through hole, thus defining an annular air-guiding channel therebetween, which can receive the airflow generated by the cooling fan and guide the airflow to enter the cylindrical housing via the upstream through holes, so that the heat generated therein can be dissipated effectively. Thus, heat is not easy to accumulate in the motor, and the performance and service life of the motor can be increased.

(a) TECHNICAL FIELD OF THE INVENTION

The present invention relates to a motor and, more particularly, to a motor with a heat dissipation structure capable of restraining temperature therein, wherein the motor is provided with a hollow hood at its housing for collecting the air current generated by a cooling fan provided at a rotating shaft of the motor, wherein one portion of the hollow hood is located above at least one upstream through hole of the motor's housing, so that the air current can quickly enter the housing via the upstream through hole to dissipate heat therein, and thus the performance and service life of the motor can be increased.

(b) DESCRIPTION OF THE PRIOR ART

Today, motors are widely used in industry for providing mechanical power. When a motor, irrespective of lower or high power, is running, the rotor assembly (including an armature core formed by an iron core wound with enameled wire, a commutator, a brush unit, etc.) and the magnets in the motor's housing will generate heat and thus cause a temperature rise. In particular, the heat accumulated in the motor's housing may cause the brush unit to contain more carbon deposits, thus affecting the electrical circuit of the motor. Besides, high temperature resulting from the armature core may reduce the magnetic intensity of the magnets used in the motor. Thus, the performance of the motor will be gradually reduced.

Currently, emergency repair kits, which are commonly used in daily life, employ a low-power motor to drive a compressor unit therein for repairing punctured tires. However, in some countries, the Traffic Act stipulates that, when a tire being punctured happens to a vehicle on a highway, the driver should repair the punctured tire within a specified period and should immediately drive away after the repair is completed to prevent rearward bump. Under these circumstances, for completing the repair as soon as possible, the motor of the compressor unit of an emergency repair kit should be operated at a higher speed. However, if the heat accumulated in the motor's housing cannot be quickly taken away, the performance of the motor will decrease. Even worse, the enameled wire of the armature core will probably be damaged to cause a short circuit, and thus the motor may burn out.

For solving this problem, a motor is usually installed with a cooling fan at its output shaft. However, the airflow induced by the cooling fan can only flow along the outer surface of the motor's housing. Thus, the heat generated by the armature core, especially the enameled wire, in the motor is not easy to be taken away. The problem of a motor being subject to heat accumulation has not yet been overcome.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a motor with a heat dissipation structure, wherein the housing of the motor is provided with a hollow hood for collecting the air current generated by a cooling fan provided at a rotating shaft of the motor. The housing defines at least one upstream through hole and at least one downstream through hole. The hollow hood is mounted to the housing such that a head portion thereof is located above the upstream through hole. The air current can be effectively collected by the hollow hood to enter the housing via the upstream through hole and finally to go out of the housing via the downstream through hole, so that the heat generated by the rotor assembly in the housing can be quickly taken away. Thus, heat is not easy to accumulate in the housing, maximum power output of the motor can be achieved, and the performance and service life of the motor can be increased.

Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a 3-dimensional view of a motor according to one embodiment of the present invention.

FIG. 2 shows a 3-dimensional view of the motor, which is viewed from a different angle than FIG. 1.

FIG. 3 shows a partially exploded view of the motor.

FIG. 4 shows a plan view of the motor.

FIG. 5 shows a sectional view of the motor taken along line A-A in FIG. 4, wherein the air current generated by a cooling fan is demonstrated.

FIG. 6 shows a sectional view of the motor taken along line B-B in FIG. 4, wherein the air current generated by the cooling fan is demonstrated.

FIG. 7 shows a sectional view of the motor taken along line C-C in FIG. 4, wherein the air current generated by the cooling fan is demonstrated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Since motors are commonly used devices, the principles of a motor's operation are not illustrated in the following paragraphs. However, basic elements of a motor will be described in this specification. Referring to FIGS. 1 through 7, a motor according to one embodiment of the present invention is shown, which includes a cylindrical housing 1, in which a rotor assembly and two opposite magnets 12 are provided. The rotor assembly includes a rotating shaft 16, an armature core formed by an iron core 171 wound with enameled wire 172, and a commutator 173. The two opposite magnets 12 are provided at an inner surface of the cylindrical housing 1. The housing 1 has a circumferential wall which terminates at a flat closure wall 101 (a front end of the motor). The flat closure wall 101 is provided with a first bearing 11 at its center and defines a plurality of downstream through holes 103 around the first bearing 11. A first end of the rotating shaft 16 is mounted to the first bearing 11 (see FIG. 2). The circumferential wall of the housing 1 defines a plurality of upstream through holes 10 for allowing outside air to enter the housing 1. A sleeve 3, which is made of a magnetically permeable metal, is closely fitted around the cylindrical housing 1, so as to increase the performance of the motor.

A cover 2 is provided with a second bearing 21 at its center and mounted to a rear end of the housing 1 opposite to the flat closure wall 101. A second end of the rotating shaft 16 of the rotor assembly is mounted at the second bearing 21 (see FIG. 1). A cooling fan 4 is installed to the second end of the rotating shaft 16 of the rotor assembly, near the cover 2. The cover 2 defines a plurality of air inlets 22, 23, which allow outside air to enter the housing 1 to dissipate heat therein.

A primary feature of the present invention is that a hollow hood 5 is provided at a front portion of the cylindrical housing 1 near the cooling fan 4 for collecting the air current generated by the cooling fan 4. The hollow hood 5 has a neck portion 51, a head portion 52, and a gradually enlarged transitional portion between the neck portion 51 and the head portion 52, wherein the neck portion 51 opens out at a first opening 510 while the head portion 52 opens out at a second opening 520 which is opposite to the first opening 510. The hollow hood 5 is mounted to the cylindrical housing 1 such that the neck portion 51 is closely fitted around the cylindrical housing 1 while the head portion 52 is located above the through holes 10, thus defining an annular air-guiding channel 6 therebetween which communicates with the through holes 10, and forming an intercepting surface 7 at an inner surface of the gradually enlarged transitional portion of the hollowing hood 5. The hollow hood 5 is a bell-shaped body, so that the annular air-guiding channel 6 has a cross-sectional dimension which increases gradually as extending from the intercepting surface 7 to the second opening 520 of the hollow hood 5. In this embodiment, as shown in FIG. 3, the first opening 510 of the hollow hood 5 is a circular opening, which has a diameter of (Y); the second opening 520 of the hollow hood 5 is a circular opening, which has a diameter of (X); the gradually enlarged transitional portion of the hollow hood 5 generally has an internal diameter of (Z) at its intercepting surface 7; wherein the relationship of X>Y and X>Z and Y=Z is fulfilled. The hollow hood 5 can be mounted to the cylindrical housing 1 via the first opening 510, wherein the neck portion 51 of the hollow hood 5 is closed fitted around the front portion of the cylindrical housing 1; the head portion 52 is located above the cylindrical housing 1 and the upstream through holes 10 and thus is not in contact with the cylindrical housing 1. The annular air-guiding channel 6 is defined between the head portion 52 of the hollow hood 5 and the cylindrical housing 1, and the through holes 10 are located between the intercepting surface 7 and the second opening 520 of the hollow hood 5, so that the air current can pass through the annular air-guiding channel 6 and the through holes 10 to enter the cylindrical housing 1 to take away the heat generated therein. The intercepting surface 7 of the hollow hood 5 can intercept the air current entering the annular air-guiding channel 6 to facilitate it to pass through the through holes 10 to enter the housing 1.

In operation, as shown in FIG. 5, in addition to some of the air current generated by the cooling fan 4 being able to enter the housing 1 via the air inlets 22, 23 defined at the cover 2, most of the air current generated by the cooling fan 4 can be collected by the hollow hood 5, wherein the intercepting surface 7 can intercept or block the air current entering the annular air-guiding channel 6, so that the air current can pass through the upstream through holes 10 to enter the cylindrical housing 1 more easily. After the air current enters the cylindrical housing 1, the heat generated by the brush unit 192, the commutator 173 (see FIG. 6), and the iron core 171 wound with the enameled wire 172 (see FIG. 7) can be taken away and finally the air current can flow out of the housing 1 via the downstream through holes 103, so that heat is not easy to accumulate in the housing 1 and thus the service life of the motor can be increased. In addition, if the diameter of the cooling fan 4 is larger than that of the second opening 520 of the hollow hood 5, some of the air current generated by the cooling fan 4 may pass over the hollow hood 5 to flow along the outer surface of the circumferential wall of the cylindrical housing 1 and the sleeve 3 to cool down the housing 1 (see FIG. 5).

As a summary, the hollow hood 5 of the motor of the present invention can effectively collect the air current generated by the cooling fan 4, so that the air current can quickly enter the cylindrical housing 1 via the upstream through holes 10 to dissipate the heat generated therein. As such, heat is not easy to accumulate in the housing and thus the performance and service life of the motor can be increased. 

I claim:
 1. In a motor including a cylindrical housing, a cooling fan, and a rotating shaft, the cylindrical housing defining at least one upstream through hole at its circumferential wall, the cooling fan being mounted at the rotating shaft for generating an air current towards the cylindrical housing for dissipating the heat generated in the motor; wherein the improvement comprises: a hollow hood is provided for collecting the air current generated by the cooling fan, the hollow hood having a neck portion, a head portion, and a gradually enlarged transitional portion integrally formed between the neck portion and the head portion, the neck portion opening out at a first opening, the head portion opening out at a second opening which is opposite to the first opening, the hollow hood being mounted to the cylindrical housing, near the cooling fan, such that the neck portion is closely fitted around the cylindrical housing, and the head portion of the hollow hood is located above the upstream through hole, thus defining an annular air-guiding channel therebetween which communicates with the upstream through hole, and forming an intercepting surface at an inner surface of the gradually enlarged transitional portion of the hollow hood, the upstream through hole being located between the intercepting surface and the second opening of the hollow hood, whereby the air current can quickly pass through the annular air-guiding channel and the upstream through hole to enter the cylindrical housing to take away the heat generated therein.
 2. The motor of claim 1, wherein the first opening of the hollow hood is a circular opening; the second opening of the hollow hood is a circular opening; the hollow hood is a bell-shaped body, so that the annular air-guiding channel has a cross-sectional dimension which increases gradually as extending from the intercepting surface to the second opening of the hollow hood.
 3. The motor of claim 2, wherein the first opening of the hollow hood has a diameter of (Y), the second opening of the hollow hood has a diameter of (X), and the gradually enlarged transitional portion of the hollow hood generally has an internal diameter of (Z) at its intercepting surface, wherein the relationship of X>Y and X>Z and Y=Z is fulfilled. 